Magnetic fixation apparatus for percutaneous catheter

ABSTRACT

A catheter apparatus can include a first magnet coupled to a catheter and a second magnet configured to couple to a patient&#39;s skin. When the catheter and the first magnet are positioned within a patient&#39;s body, the second magnet can exert a magnetic force on the first magnet that stabilizes the catheter relative to the second magnet. The second magnet can be directly attached to the patient&#39;s skin or secondary devices such as straps can be used to place the second magnet in a fixed position relative to the patient&#39;s body. In some implementations, a plurality of magnets can facilitate holding the catheter in a substantially fixed position within the patient.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/274,546, filed Feb. 13, 2019, now allowed, which application is acontinuation of U.S. application Ser. No. 15/095,932, filed Apr. 11,2016, now U.S. Pat. No. 10,238,782. The disclosures of the foregoingapplications are hereby incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

Percutaneous catheters are inserted into the vascular system of apatient as part of numerous therapeutic and diagnostic procedures. Forexample, a percutaneous mechanical circulatory support device, alsocommonly referred to as a heart pump, can be introduced into thevascular system of a patient through the femoral artery and insertedinto the heart (e.g., the left ventricle) to pump blood from the heartinto a blood vessel (e.g., the aorta). This pumping action can assistthe natural cardiac pump function or replace the natural cardiac pumpfunction. Percutaneous catheters may also be used for other proceduressuch as angioplasty, electrophysiology study, and ablation.

It is often desirable to fix a percutaneous catheter at a particularlocation within a patient. In the more specific case of a heart pump,for example, it is desirable for the pump to remain fixed in place in aposition that optimizes the flow of blood from the heart and into theblood vessel. If the heart pump strays too far in or out from thisoptimal position in the heart, reduced flow and/or other complicationsmay arise. For example, when the pump is positioned too far in the leftventricle such that the inlet and the outlet port(s) are both within theventricle, the device can cause blood to circulate within the leftventricle rather than being delivered into the ascending aorta, therebydecreasing the support provided to the patient. Additionally, if theoutlet port(s) of the heart pump moves it may be blocked by leaflets ofa valve (e.g., the aortic valve). Blood delivered by the heart pump mayimpinge on the valve, which can cause lysing of blood cells or hemolysisdue to shear stress. When the device is in such a position, the valvemay also interfere with the flow of blood through the device, decreasingthe support provided to the patient.

It may be desirable for a percutaneous catheter to remain in a patientfor a long period of time, such as for a patient who requires long-termassistance with cardiac pumping. However, when a percutaneous catheterremains in a patient for a long period of time, it can be more difficultto maintain the position of the percutaneous catheter in the patient.Movement of the patient can cause the percutaneous catheter to strayfrom its desired position. For percutaneous catheters that are insertedinto the heart of a patient, the normal pulsatility of the heart cancause the catheter to stray from its desired position and this canrequire user intervention.

One solution for maintaining the position of a percutaneous catheter isto reduce slack in the catheter to reduce the possibility of movement.Another solution for maintaining the position of a percutaneous catheterinserted into the heart is a flexible atraumatic extension that extendsfrom the distal end of the catheter. This extension may reduce thepossibility of the percutaneous catheter slipping too far from itsoptimal position into the heart. However, other solutions would bedesirable in addition to or instead of these mechanisms. Additionally,it may be desirable to fix the orientation of the catheter within thebody of the patient to optimize system performance.

BRIEF SUMMARY OF THE INVENTION

Disclosed herein are apparatuses and methods for magnetically fixating,anchoring, or stabilizing a percutaneous catheter, for example, inlong-term heart assist settings. A first magnet is coupled to thepercutaneous catheter and a second magnet is coupled to the patient (orother stable structure) and substantially fixed in position andorientation. For example, the second magnet may be enclosed in a patchfixed to the patient's skin, for example by adhesive. The first andsecond magnets exert an attractive magnetic force on each other. Theattractive magnetic force will cause little change in the position ofthe second magnet because the second magnet is substantially fixed inposition to the patient or other stable structure. The first magnet willbe drawn by the attractive magnetic force to the second magnet. As thefirst magnet is drawn to the second magnet, the first magnet will drawthe catheter to which it is coupled along with it. At a certain positionrelative to the second magnet, external forces (e.g., the opposing forceof the patient's internal tissue) will prevent the first magnet and thecatheter from moving further towards the second magnet. In the absenceof other external forces, the first magnet and catheter will remainsubstantially fixed at that position.

If the first and second magnets are each sufficiently elongate, thefirst and second magnets may be used to cause the catheter to assume apreferred orientation within a plane (e.g., the coronal plane) of thepatient. The length of the second magnet may allow the second magnet tobe attached to the skin of the patient within the coronal plane of thepatient at a pre-determined angle relative to the patient's longitudinalaxis. Similarly, the length of the first magnet may allow the firstmagnet to be attached to the catheter at a pre-determined angle relativeto the longitudinal axis of the catheter. Upon insertion of the catheterand the first magnet into the vasculature of the patient, the north andsouth poles of the first magnet and the south and north poles of thesecond magnet, respectively, may align. The pre-determined angles of thefirst and second magnets can be chosen such that upon alignment of thepoles of the first and second magnets, the catheter assumes a certainangle relative to the patient's longitudinal axis within the patient'scoronal plane. This can allow the catheter to be fixed in a preferredorientation relative to the patient's heart, blood vessels, and othersurrounding anatomical features. Since the optimal catheter orientationcan vary from patient to patient, the preferred orientation can bedetermined based on the anatomies of multiple individuals (e.g., >20individuals, >50 individuals, >100 individuals, >500 individuals, or anyother suitable number) with different characteristics (e.g., ages,sizes, genders, etc.). The preferred catheter orientation can beselected to accommodate a certain percentage of patient anatomies (e.g.,80%, 90%, 95%, or any other suitable percentage) of the anatomies of theanalyzed individuals. In some implementations, the first magnet includesa first group of two or more spatially separated magnets, and the secondmagnet includes a second group of two or more spatially separatedmagnets. In such implementations, torque can be applied to the catheter(e.g., in the coronal plane) by simultaneously applying oppositelydirect forces to two magnets in the first group of magnets using thesecond group of magnets. This can also allow the catheter to be fixed ina preferred orientation relative to the patient's heart, blood vessels,and other surrounding anatomical features.

Substantially fixating the position and/or orientation of the cathetercan improve the effectiveness of the therapeutic and/or diagnosticprocedures to which the catheter is directed. For example, substantiallyfixating a percutaneous catheter configured as a heart pump in itsoptimal position and/or orientation within the heart can improve cardiacassistance. Substantially fixating the position and orientation of thecatheter may be especially beneficial for therapeutic or diagnosticprocedures requiring a catheter to remain in a patient's vasculature fora long period of time, because the catheter would be less likely tostray from its optimal position and orientation during a long-termprocedure.

In one aspect, a catheter apparatus comprises a first magnet coupled toa catheter and a second magnet configured to couple to a patient (e.g.,to the patient's skin). The second magnet exerts a magnetic force on thefirst magnet that stabilizes the catheter relative to the second magnetwhen the catheter and the first magnet are positioned inside of thepatient's body.

In some implementations, the second magnet is sized to be supported bythe patient's body. In certain implementations, the second magnetincludes an adhesive coating configured to fix the second magnet to thepatient's skin. In some implementations, the second magnet is enclosedwithin a patch that is configured to couple to the patient's skin.

In some implementations, the first magnet is coated with ananti-corrosive layer, compound, or material. In certain implementations,the catheter apparatus further comprises a heart pump coupled to adistal end portion of the catheter. The first magnet may be positionedproximal or distal relative to the heart pump. In some implementations,the catheter further comprises a distal portion and the first magnet iscoupled to the distal portion.

In certain implementations, the surface area of the first magnet facingthe patient's skin is approximately equal to 25 square millimeters. Insome implementations, the surface area of the second magnet in contactwith the patient's skin is approximately equal to 25 square millimeters.In certain implementations, the attractive force generated by the firstand second magnets is about 2.5 N. In some implementations, the firstmagnet and the second magnet each have a north and south pole, and thefirst magnet is coupled to the catheter at a predetermined orientationrelative to the catheter such that the catheter assumes a preferredorientation relative to the patient.

In another aspect, a method for percutaneously inserting a catheter intoa patient comprises inserting a catheter into the patient's vasculature,the catheter having a first magnet, and positioning a second magnet in afixed position relative to the patient such that the first and secondmagnets are aligned and exert a force on each other, thereby stabilizingthe position of the catheter relative to the second magnet.

In some implementations, positioning the second magnet in a fixedposition relative to the patient comprises attaching the second magnetto the patient's skin with adhesive. In certain implementations thesecond magnet is included within a patch and the patch is directlyattached to the patient's skin.

In some implementations, the first magnet is coupled to a distal portionof the catheter. In certain implementations, the catheter furthercomprises a heart pump disposed at an end portion of the catheter, andthe first magnet is coupled to a distal end portion of the heart pump.

In some implementations, the magnetic force between the first and secondmagnets is about 2.5 N. In certain implementations, the first magnet andthe second magnet each have a north and south pole, and the first magnetis coupled to the catheter at a predetermined orientation relative tothe catheter such that the catheter assumes a preferred orientationrelative to the patient.

Variations and modifications will occur to those of skill in the artafter reviewing this disclosure. The disclosed features may beimplemented, in any combination and subcombination (including multipledependent combinations and subcombinations), with one or more otherfeatures described herein. The various features described or illustratedabove, including any components thereof, may be combined or integratedin other systems. Moreover, certain features may be omitted or notimplemented.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects and advantages will be apparent uponconsideration of the following detailed description, taken inconjunction with the accompanying drawings, in which like referencecharacters refer to like parts throughout, and in which:

FIG. 1 shows an apparatus for magnetically fixating a percutaneouslyinserted catheter according to certain implementations;

FIG. 2 is a side view of a patient and an apparatus for magneticallyfixating a percutaneously inserted catheter according to certainimplementations;

FIG. 3 is a magnified view of the apparatus of FIG. 2;

FIG. 4 shows an illustrative configuration of a catheter that includesmagnetic fixation distal to its pump;

FIG. 5 is a cross-sectional view of a patch for a second magnetaccording to certain implementations;

FIG. 6 is a perspective view of the patch of FIG. 5;

FIG. 7 shows a strap for coupling a second magnet to the skin of apatient according to certain implementations;

FIG. 8 shows a patient and an illustrative apparatus for magneticallyfixating a percutaneously inserted catheter, the apparatus having aplurality of magnets; and

FIG. 9 is a flow diagram of an illustrative process for percutaneouslyinserting a catheter into a patient.

FIG. 10 is a cross section of a heart showing two rotational positionsof a catheter within the heart.

DETAILED DESCRIPTION

To provide an overall understanding of the apparatuses and methods formagnetically fixating a percutaneously inserted catheter, certainillustrative embodiments will be described. Although the embodiments andfeatures described herein are specifically described for use inconnection with percutaneously inserted catheters, it will be understoodthat all the components and other features outlined below may becombined with one another in any suitable manner and may be adapted andapplied to other types of therapeutic and diagnostic devices andmethods.

The apparatuses and methods described herein provide an apparatus formagnetically fixating, anchoring, and/or stabilizing a percutaneouscatheter using magnets. For example, the percutaneous catheter includesa first magnet that is coupled to, attached to, fixed to, or positionedon the catheter and a second magnet that is coupled to, attached to,fixed to, or positioned on the patient in a substantially fixed positionand orientation. For example, the second magnet may be enclosed in apatch that is fixed to the patient's skin, such as by adhesive. Thefirst and second magnets exert an attractive magnetic force on eachother. The attractive magnetic force will cause little to no change inthe position of the second magnet because the second magnet issubstantially fixed in position, while the first magnet will be drawn bythe attractive magnetic force to the second magnet. As the first magnetmoves toward the second magnet, the first magnet will also move thecatheter to which it is coupled along with it. At a certain relativeposition between the first magnet and the second magnet, external forces(e.g., the opposing force of the patient's internal tissue) will preventthe first magnet and the catheter from moving further towards the secondmagnet. In the absence of other external forces, the first magnet andthe catheter will remain substantially fixed at that position.

In some implementations, the second magnet is elongate (e.g., 1 mm, 2.5mm, 5 mm, 7.5 mm, 10 mm, 50 mm, 10 cm, 30 cm, >30 cm long). The lengthof the second magnet allows the second magnet to be attached to the skinof the patient within the coronal plane of the patient at apre-determined angle relative to the patient's longitudinal axis.Similarly, the first magnet may be elongate (e.g., 1 mm, 2.5 mm, 5 mm,7.5 mm, 10 mm, 50 mm, 10 cm, 30 cm, >30 cm long). The length of thefirst magnet allows the first magnet to be attached to the catheter at apre-determined angle relative to the longitudinal axis of the catheter.Upon insertion of the catheter and the first magnet into the vasculatureof the patient, the north and south poles of the first magnet and thesouth and north poles of the second magnet, respectively, may align. Thepre-determined angles of the first and second magnets can be chosen suchthat upon alignment of the poles of the first and second magnets, thecatheter assumes a certain angle relative to the patient's longitudinalaxis within the patient's coronal plane. This can allow the catheter tobe fixed in a preferred orientation relative to the patient's heart,blood vessels, and other surrounding anatomical features. In someimplementations, the first magnet includes a first group of two or morespatially separated magnets, and the second magnet includes a secondgroup of two or more spatially separated magnets. In suchimplementations, torque can be applied to the catheter (e.g., in thecoronal plane) by simultaneously applying oppositely direct forces totwo magnets in the first group of magnets using the second group ofmagnets. This can also allow the catheter to be fixed in a preferredorientation relative to the patient's heart, blood vessels, and othersurrounding anatomical features.

Substantially fixating a percutaneous catheter configured as a heartpump in its optimal position and orientation within the heart canimprove cardiac assistance. Substantially fixating the position andorientation of the catheter may be beneficial for long-term procedures,because the catheter would be less likely to stray from its optimalposition and orientation during the long-term procedure.

FIG. 1 shows an apparatus 101 for magnetically fixating a percutaneouslyinserted catheter according to certain implementations. The apparatus101 includes a catheter 103, a first magnet 107, and a second magnet109. The first magnet 107 is coupled to the catheter 103. The secondmagnet 109 is coupled to the patient 111 (e.g., directly attached to thepatient's skin). The first magnet 107 and the second magnet 109 exert anattractive magnetic force 113 (e.g., through the skin and tissue) oneach other. The attractive magnetic force 113 will cause little changein the position of the second magnet 109 because the second magnet 109is substantially fixed in position. The first magnet 107 will be drawnby the attractive magnetic force 113 to the second magnet 109. As thefirst magnet 107 moves toward the second magnet 109, the first magnet107 will move the catheter 103 to which it is coupled along with it. Ata certain position relative to the second magnet 109, external forces(e.g., the opposing force of the patient's internal tissue) will preventthe first magnet 107 and the catheter 103 from moving further towardsthe second magnet 109, thereby leaving the two magnets in a stableposition relative to each other. In the absence of other externalforces, the first magnet 107 and the catheter 103 will remainsubstantially fixed at that position.

Substantially fixating the position and/or orientation of the catheter103 can improve cardiac assistance because the catheter 103 is morelikely to remain at an optimal position and orientation. In particular,fixating the catheter 103 can prevent a blood inlet of the blood pumpfrom suctioning against the wall of the heart which could cause blockageof the blood flow. Additionally, fixating the catheter 103 can preventthe blood outlet from being positioned too close to a feature of thepatient's anatomy (e.g., the aortic valve) which could cause the exitingblood to experience relatively high shear stress and hemolysis.Furthermore, fixating the catheter 103 can prevent the blood outlet frombeing positioned in the same heart chamber as the blood inlet, whichcould cause recirculation of blood within the same heart chamber withoutsubstantially improving cardiac output.

The attractive magnetic force 113 generated using the apparatus 101 canbe estimated using the Gilbert Model for calculating the force betweenmagnetized surfaces:

F=(B _(n) ² ·A)/(2·μ₀)

where F is the magnetic force, B_(n) is the flux density, A is thesurface area, and μ₀ is the permeability of space, which equals 4π×10⁻⁷T·m/A. In the example of FIG. 1, the magnetic field due to the firstmagnet 107 and the second magnet 109 can be about B_(n)=0.5 T.Additionally, an appropriate size of the surface area of the magnetsfacing or contacting the patient's skin is about A=25 mm². Therefore,the magnetic force of attraction generated is about 2.5 N. In someimplementations, the magnetic force is more than 2.5 N (e.g., 3 N, 5 N,10 N, >10 N). In certain implementations, the magnetic force is lessthan 2.5 N (e.g., 2 N, 1 N, 0.5 N, 0.1 N, <0.1 N).

FIG. 2 is a side view of a patient and an apparatus 201 for magneticallyfixating a percutaneously inserted catheter according to certainimplementations. FIG. 3 is a magnified view of the apparatus of FIG. 2.The apparatus 201 includes a catheter 203, a first magnet 207, a secondmagnet 209, and a patch 205. The catheter 203 is configured as a heartpump. In certain implementations, the catheter 203 may be any othersuitable type of percutaneously inserted catheter (for example,configured for procedures such as angioplasty, electrophysiology study,or ablation). As shown, the catheter 203 includes a heart pump 215 at anend portion 221 of the catheter 203. The first magnet 207 is coupled tothe catheter 203 and the second magnet 209 is enclosed in the patch 205.The patch 205 is coupled to the skin of a patient 211 by adhesive 227coated on the surface of the patch 205.

The catheter 203 may be inserted into a patient's vasculature at variousaccess points, such as through an artery for left heart support orthrough a vein for right heart support. For example, in FIG. 2 thecatheter 203 is inserted into the femoral artery (not shown) in the legof the patient 211. The catheter 203 is passed through the vasculatureof the patient 211 until the end portion 221 of the catheter 203 reachesits destination. In FIG. 2, the end portion 221 is positioned in theleft ventricle of the heart 223 of the patient 211 and extends acrossthe aortic valve into the aorta. In some implementations, the distalportion 221 is positioned entirely or partially within the leftventricle, the right ventricle, the atria, the aorta, the pulmonaryvein, or any other suitable location.

The end portion 221 includes a heart pump 215 for pumping blood from achamber of the heart 223 (e.g., the left ventricle) into a blood vesselof the patient 211 (e.g., the aorta). This pumping action may assist thenatural cardiac pumping function or replace the natural cardiac pumpingfunction. The heart pump 215 includes a drive shaft (which may be drivenby a motor within the heart pump 215 or external to the heart pump 215),one or more impeller blades driven by the drive shaft, a blood inlet,and a blood outlet. Rotation of the impeller blades draws blood from achamber of the heart 223 into the heart pump 215 through one or morewindows in the blood inlet and out of the heart pump 215 through one ormore windows in the blood outlet to a blood vessel. In the example ofFIG. 2, the catheter 203 includes a flexible atraumatic extension 219(e.g., a pigtail) at its distal end to reduce the possibility of thecatheter 203 slipping too far from its optimal position into the heart223 of the patient 211.

The first magnet 207 of the catheter can vary in any number of ways. Asshown, the first magnet 207 is attached to the catheter 203. The firstmagnet 207 can be coupled to the catheter 203 in various ways, such asby a fixture, an interference fit, an interlocking connection, adhesive,fasteners, straps, or any other suitable coupling means. The firstmagnet 207 can have various shapes and configurations. As shown, thefirst magnet 207 is generally tubular and has an outer surface 231 and abore 233 through which the catheter 203 extends. While a tubular firstmagnet 207 is shown, in some implementations the first magnet 207 iscubical, spherical, cylindrical, toroidal, or any other suitable shape.The first magnet has a north pole 235 and a south pole 237.Additionally, the first magnet 207 may be any type of magnet. Forexample, the first magnet 207 may be a permanent magnet or may becomprised of a soft magnetic material, such as an iron-chromium-aluminum(FeCrAl) alloy (e.g., KANTHAL® manufactured by Sandvik). In someimplementations, the surface area of the first magnet 207 facing thepatient's skin may be approximately 25 mm² or less. For other examples,the surface area of the first magnet 207 facing the patient's skin maybe 20 mm², 15 mm², 10 mm², 5 mm², <5 mm², or any other appropriatesurface area. In some implementations, the surface area of the firstmagnet 207 facing the patient's skin may be greater than 25 mm². Forother examples, the surface area of the first magnet 207 facing thepatient's skin may be 30 mm², 40 mm², 50 mm², >50 mm², or any otherappropriate surface area.

In implementations where the first magnet 207 is a rare earth magnet, itis preferable to coat, encase, enclose, or hermetically seal the firstmagnet 207 with a layer, compound, or material (e.g., coated or encasedwith a biocompatible material/biocompatible metallic material such asstainless steel, aluminum, gold, platinum, etc.) to reduce corrosion,because rare earth magnets may corrode in the bloodstream of the patient211.

In FIG. 2, the first magnet 207 is coupled to the catheter 203 proximalto the heart pump 215 and is located at the approximate height of theheart 223 of the patient 211. Although the first magnet 207 is depictedin this location, the first magnet 207 may be coupled to the catheter203 at any suitable location along the length of the catheter 203. Forexample, the first magnet 207 may be coupled to the flexible atraumaticextension 219, to a distal end portion/cannula of the heart pump 215, tothe catheter 203 distal to the heart pump 215, or to the catheter 203proximal to the heart pump 215 and located at the approximate height ofthe abdomen of the patient 211. The location of the first magnet 207relative to the body of the patient 211 is preferably determined by thelocation along the catheter 203 at which the first magnet 207 is coupledto the catheter 203 and how far into the patient's vasculature thecatheter 203 is inserted.

The position of the first magnet 207 relative to the motor of the heartpump 215 is an important consideration. The magnetic field generated bythe first magnet 207 may interfere with the performance of the motor ofthe heart pump 215 if the first magnet 207 and the motor of the heartpump 215 are positioned too close to each other. Distances that may betoo close include 1 mm, 5 mm, 1 cm, 2 cm, 3 cm, 4 cm, 5 cm, 10 cm, 15cm, >15 cm, or other distances. This is especially important when theheart pump 215 is too small to accommodate a yoke, magnetic amplifier,or magnetic reflux jacket around the motor that could serve as a barrierto external magnetic fields. For example, the heart pump 215 may be toosmall to accommodate a yoke when the heart pump 215 has an outerdiameter of 12 Fr (4 mm) to 14 Fr (4.67 mm). When the heart pump 215 isphysically large (e.g., 21 Fr (7 mm) in diameter), it can accommodate alarge yoke, magnetic amplifier, or magnetic reflux jacket which canserve as a barrier to external magnetic fields. With a heart pump 215having a large yoke, magnetic amplifier, or magnetic reflux jacket,positioning of the first magnet 207 relative to the motor of the heartpump 215 can be less critical. The position of the first magnet 207relative to the heart pump 215 can also determine if a portion of theheart pump 215 is drawn to a wall of a heart chamber. If the firstmagnet 207 is located nearby the heart pump 215, the attraction of thesecond magnet 209 may pull the heart pump 215 against a wall of theheart 223. If the portion of the heart pump 215 containing the bloodinlet becomes stuck against the wall of the heart 223, the inlet may beblocked, thus impeding cardiac assistance. If the portion of the heartpump 215 containing the blood outlet becomes stuck against the wall ofthe heart 223, the exiting blood may experience relatively high shearstress, thereby causing hemolysis. To reduce the risk of both problems,it may be preferable to space the first magnet 207 from the heart pump215 by an appropriate distance (e.g., 1 mm, 5 mm, 1 cm, 2 cm, 3 cm, 4cm, 5 cm, 10 cm, 15 cm, >15 cm, or any other suitable distance).

The second magnet 209 can have various shapes and configurations. Asshown, the second magnet 209 is substantially flat. In someimplementations, the second magnet 209 is disk-shaped, cubical,spherical, cylindrical, toroidal, box-shaped, planar, or any otherappropriate shape. The second magnet 209 has a north pole 239 and asouth pole 241. The second magnet 209 may be any suitable type ofmagnet. For example, the second magnet 209 may be a permanent magnet ormay be comprised of a soft magnetic material, such as aniron-chromium-aluminium (FeCrAl) alloy (e.g., KANTHAL® manufactured bySandvik). In some implementations, the surface area of the second magnet209 in contact with the patient's skin may be approximately 25 mm² orless. For other examples, the surface area of the second magnet 209 incontact with the patient's skin may be 20 mm², 15 mm², 10 mm², 5 mm², <5mm², or any other appropriate surface area. In some implementations, thesurface area of the second magnet 209 in contact with the patient's skinmay be greater than 25 mm². For other examples, the surface area of thesecond magnet 209 in contact with the patient's skin may be 30 mm², 40mm², 50 mm², >50 mm², or any other appropriate surface area.

As described above, the second magnet 209 is coupled to the skin of thepatient 211. In FIGS. 2-3, the second magnet 209 is enclosed within apatch 205. The patch 205 is configured to physically couple to the skinof the patient 211 in a substantially fixed position and orientation.The patch 205 may be composed of fabric, plastic, latex, or any otherappropriate material. The patch 205 may be coupled to the patient 211 atvarious locations, or to other stable locations outside the patient. Forexample, in FIG. 2, the patch 205 is coupled to the upper back of thepatient 211, at the approximate height of the heart 223 of the patient211. In some implementations, the patch 205 is coupled to the lower backof the patient 211. In certain implementations, the patch 205 is coupledto the patient 211 on the upper chest of the patient 211 at theapproximate height of the heart 223 of the patient 211. In someimplementations, the patch 205 is coupled to the front abdomen region ofthe patient 211. The patch 205 is coupled to the patient 211 by anadhesive 227 coated on a surface of the patch 205.

If the first magnet 207 and the second magnet 209 are each sufficientlyelongate, the first magnet 207 and the second magnet 209 may be used tocause the catheter 203 to assume a preferred orientation within a plane(e.g., the coronal plane) of the patient 211. For example, the secondmagnet 109 may be 1 mm, 2.5 mm, 5 mm, 7.5 mm, 10 mm, 50 mm, 10 cm, 30cm, or >30 cm long. The length of the second magnet 209 allows thesecond magnet 109 to be attached to the skin of the patient within thecoronal plane of the patient at a pre-determined angle relative to thepatient's longitudinal axis. Similarly, the first magnet 107 may be 1mm, 2.5 mm, 5 mm, 7.5 mm, 10 mm, 50 mm, 10 cm, 30 cm, or >30 cm long.The length of the first magnet 207 allows the first magnet 207 to beattached to the catheter 203 at a pre-determined angle relative to thelongitudinal axis of the catheter 203. Upon insertion of the catheter203 and the first magnet 207 into the vasculature of the patient 211,the north pole 235 and the south pole 237 of the first magnet 207 andthe south pole 241 and the north pole 239 of the second magnet 209,respectively, align. The pre-determined angles of the first magnet 207and the second magnet 209 can be chosen such that upon alignment of thepoles of the first magnet 207 and the second magnet 209, the catheter203 assumes a certain angle relative to the patient's longitudinal axiswithin the patient's coronal plane. This can allow the catheter 203 tobe fixed in a preferred orientation relative to the patient's heart,blood vessels, and other surrounding anatomical features. In someimplementations, the first magnet 207 includes a first group of two ormore spatially separated magnets, and the second magnet 209 includes asecond group of two or more spatially separated magnets. In suchimplementations, torque can be applied to the catheter (e.g., in thecoronal plane) by simultaneously applying oppositely direct forces totwo magnets in the first group of magnets using the second group ofmagnets. This can also allow the catheter 203 to be fixed in a preferredorientation relative to the patient's heart, blood vessels, and othersurrounding anatomical features.

Substantially fixating the position and/or orientation of the catheter203 using the apparatus 201 can improve cardiac assistance by preventingthe catheter 203 from straying/moving from its desired or optimalposition. Because the catheter 203 is more likely to move from itsoptimal position/orientation during a long-term procedure, the magneticfixation may be especially beneficial for longer term procedures (e.g.,for catheters positioned inside of a patient for >1 hr, >2 hr, >6hr, >12 hr, >24 hr, or any other suitable length).

FIG. 4 shows an illustrative configuration of a catheter 403 thatincludes magnetic fixation distal to its pump. The catheter 403 caninclude any combination of features previously described. The catheter403 shown is configured as a heart pump. The catheter 403 includes aheart pump 415, a distal portion/cannula 421, a flexible atraumaticextension 419, and a first magnet 407. The distal portion 421 can besubstantially flexible and can be substantially straight in its restingstate or can have at least one bend in its resting state. For example,the distal portion 421 in FIG. 4 has a single bend. As will beappreciated, the distal portion 421 and the at least one bend can bestraightened during insertion (such as by advancing the distal portion421 through a vessel and/or over a guidewire) and the distal portion 421can have one or more bends when deployed into the heart. The one or morebends can facilitate positioning the distal portion 421 in a desiredaxial and rotational orientation within the heart and the one or morebends do not interfere with fluid flow therethrough. The flexibleatraumatic extension 419 reduces the possibility of the catheter 403slipping too far from its optimal position into the heart. The flexibleatraumatic extension 419 may be a pigtail tip, a rounded tip, or anyother suitable atraumatic feature. As shown, the first magnet 407 iscoupled to the distal portion 421 of the catheter 403. This coupling maybe by adhesive, fasteners, straps, or any other suitable coupling means.The first magnet 407 may have a bore through which the catheter 403passes. In certain implementations, the first magnet 407 is coupled tothe flexible atraumatic extension 419. The first magnet 407 may becoupled to a proximal end portion of the flexible atraumatic extension419, a distal end portion of the flexible atraumatic extension 419, orin a middle portion of the flexible atraumatic extension 419. In someimplementations, the first magnet 407 is coupled to a distal end portionof the heart pump 415. In certain implementations, the first magnet 407is coupled to the catheter 403 distal to the heart pump 415. In someimplementations, the first magnet 407 is coupled to the catheter 403proximal to the heart pump 415 and is located at the approximate heightof the abdomen of the patient.

FIG. 5 is a cross-sectional view of a patch 505 for a second magnet 509according to certain implementations. FIG. 6 is a perspective view ofthe patch 505 of FIG. 5. As shown, the patch 505 includes a first layer529, a second layer 531, an adhesive layer 527, and the second magnet509. The adhesive layer 527 is coated on a first outer surface 533 ofthe patch 505, the surface 533 configured to be coupled to a patient.The first layer 529 is on a second outer surface 535 of the patch 505.The second magnet 509 is embedded within the second layer 531. The firstlayer 529 and the second layer 531 may be composed of fabric, plastic,latex, or any other appropriate material. The first layer 529 and thesecond layer 531 may be composed of different materials than each other.For example, the second layer 531 may be composed of a material thatprovides better comfort against the skin of a patient, conforms betterto the shape of the patient's body, and/or is better configured forenclosing the second magnet 509. The first layer 529 may be composed ofa material that can protect the second layer 531 and the second magnet509 from external disturbances (e.g., water, contact with clothing orbedding, contact with medical instruments), provide structural integrityto the second layer 531, and/or be more amenable to interacting withpackaging. While the patch 505 may have various sizes, shapes, andconfigurations, the patch 505 is preferably small in size and lightweight. The patch 505 shown is less than 10 cm×10 cm in size. In someimplementations, the size of the patch 505 is <30 cm×30 cm, <20 cm×20cm, <5 cm×5 cm, <2 cm×2 cm, <1 cm×1 cm, or any suitable size. The patch505 shown is less than 2 cm thick. In some implementations, thethickness of the patch 505 is <5 cm, <4 cm, <3 cm, <1 cm, <0.5 cm, <1mm, or any suitable thickness. The weight of the patch 505 shown is lessthan 100 g. In some implementations, the weight of the patch 505 is <1kg, <500 gm, <50 gm, <10 gm, or any suitable weight. The patch 505 shownis rectangular in shape. In some implementations, the patch 505 issquare, circular, or any other suitable shape. One skilled in the artwill appreciate that other configurations and designs of the patch 505are possible and that the patch 505 can include more or fewer layersthan depicted. For example, the patch 505 may lack the first layer 529,or the patch 505 may include a third layer.

FIG. 7 shows a strap 701 for coupling a second magnet 709 to the skin ofa patient 711 according to certain implementations. The strap 701includes the second magnet 709 and a fastener 733. The second magnet 709is encapsulated within the strap 701. The strap 701 wraps around aportion of the body of the patient 711, such as around the patient'schest and over or under the patient's arms, and fastens together withthe fastener 733.

Other means for coupling the second magnet 709 to the patient 711 arepossible. In certain implementations, the second magnet 709 isencapsulated within a band containing an elastic material that clingsaround a portion of the body of the patient 711. In certainimplementations, the second magnet 709 is positioned directly adjacentto the skin of the patient 711 and is held in place by a bandageextending across an external surface of the second magnet 709 andadhering to the skin of the patient 711 on either side of the secondmagnet 709. An advantage of the latter coupling means is a specializedpatch, strap, or band encapsulating a magnet may not be necessary.Additionally, the bandage can be replaced without needing to replace themagnet. Although various coupling means are discussed, persons skilledin the art will appreciate that the second magnet 709 can be affixeddirectly to the skin of the patient 711 by adhesive.

A plurality of magnets can be used, for example, with any of theembodiments described above. FIG. 8 shows a patient and an illustrativeapparatus 801 for magnetically fixating a percutaneously insertedcatheter, the apparatus 801 having a plurality of magnets. As shown, theapparatus 801 includes a catheter 803, a first magnet 807, a secondmagnet 809, a third magnet 835, a fourth magnet 837, a first patch 805,and a second patch 839. The catheter 803 includes a heart pump 815, anend portion 821, and a flexible atraumatic extension 819. The flexibleatraumatic extension 819 reduces the possibility of the catheter 803slipping too far from its optimal position into the heart 823. Theflexible atraumatic extension 819 may be a pigtail tip, a rounded tip,or any other suitable atraumatic structure. The first magnet 807 iscoupled to the catheter 803 proximal to the heart pump 815 and islocated at the approximate height of the heart 823 of a patient 811. Thesecond magnet 809 is encapsulated in the first patch 805. The firstpatch 805 is coupled to the patient 811 on the upper back by adhesive onthe surface of the first patch 805. The third magnet 835 is coupled tothe flexible atraumatic extension 819. The fourth magnet is encapsulatedin the second patch 839. The second patch 839 is coupled to the patient811 on the upper chest by adhesive on the surface of the second patch839. The second magnet 809 exerts an attractive magnetic force on thefirst magnet 807 and the fourth magnet 837 exerts an attractive magneticforce on the third magnet 835. Using these additional magnets can allowa user to precisely control the fixed position of the catheter 803, canincrease how rigidly the catheter 803 is fixed in place, and/or canincrease robustness to failure of one of the multiple magnets. If thefirst magnet 807 and the third magnet 835 are sufficiently far away fromeach other (for example, 75-125 mm), their magnetic fields will notinterfere with each other substantially. Similarly, if the second magnet809 and the fourth magnet 837 are sufficiently far away from each other(for example, 75-125 mm), their magnetic will not interfere with eachother substantially. In some implementations, it may be desirable forthe first magnet 807 and the third magnet 835 to be sufficiently closetogether such that their magnetic fields interact. Similarly, in someimplementations, it may be desirable for the second magnet 809 and thefourth magnet 837 to be sufficiently close together such that theirmagnetic fields interact.

In some implementations, the second magnet 809, the fourth magnet 837,the first patch 805, and the second patch 839 are coupled to the patient811 on the same side of the body of the patient 811. In suchimplementations, the second magnet 809 and the fourth magnet 837 eachexert an attractive magnetic force on both the first magnet 807 and thesecond magnet 809. In some implementations, additional magnets arecoupled to the first patch 805 and/or the second patch 839. In certainimplementations, there may be more than two magnets coupled to thecatheter 803 and/or more than two magnets coupled to the patient 811. Insome implementations, there are multiple magnets coupled to the catheter803 but only one magnet coupled to the patient 811. In someimplementations, there are multiple magnets coupled to the patient 811but only one magnet coupled to the catheter 803.

FIG. 9 is a flow diagram 900 of an illustrative process forpercutaneously inserting a catheter into a patient. At step 902, thecatheter (e.g., catheter 103 of FIG. 1) having a first magnet (e.g.,first magnet 107 of FIG. 1) is inserted into a patient's vasculature.The first magnet may be coupled to a distal portion of the catheter. Thecatheter may include a heart pump disposed at an end portion of thecatheter, and the first magnet is coupled to a distal end portion of theheart pump. The first magnet can be coupled to the catheter at a regionproximal to the heart pump or distal to the heart pump. In someimplementations, the surface area of the first magnet that is facing thepatient's skin is 25 mm². During manufacturing, the first magnet may becoated, encased, enclosed, or hermetically sealed with an anti-corrosivelayer, compound, or material (e.g., coated or encased with abiocompatible material/biocompatible metallic material such as stainlesssteel aluminium, gold, platinum, etc.). The catheter may be insertedthrough the femoral artery and advanced along the aorta until the pumpis in a desired/optimal position (e.g., with the flexible atraumaticextension in the left ventricle away from anatomical structures and theoutlet in the aorta, proximal to the aortic valve). The position of thepump can be monitored and confirmed using various imaging techniques,such as fluoroscopy. When the pump is in the desired position, medicalpersonnel can fix the position of the pump in various ways. For example,a proximal portion of the catheter can be secured to or sutured onto thepatient's leg near the insertion site and a tuohy borst valve can beactuated to prevent the catheter from sliding proximally or distallyrelative to a repositioning sheath and the insertion site.

At step 904, a second magnet (e.g., second magnet 109 of FIG. 1) iscoupled to an external site on the patient such that the first magnetstabilizes the position of the catheter within the patient, relative tothe second magnet. Coupling the second magnet to an external area of thepatient the patient's skin can be accomplished using adhesive, such asadhesive that was coated onto the second magnet during its manufacturingphase. The second magnet may be included within a patch (e.g., patch 205of FIG. 2) and the patch may be coupled to the patient's skin such asusing adhesive coated onto the patch. In some implementations, thesurface area of the second magnet that is in contact with the patient'sskin is 25 mm².

The attractive force generated by the first and second magnets may beapproximately equal to 2.5 N. In some implementations, the magneticforce is more than 2.5 N (e.g., 3 N, 5 N, 10 N, >10 N). In certainimplementations, the magnetic force is less than 2.5 N (e.g., 2 N, 1 N,0.5 N, 0.1 N).

If the first and second magnets are each sufficiently elongate (e.g., 1mm, 2.5 mm, 5 mm, 7.5 mm, 10 mm, 50 mm, 10 cm, 30 cm, >30 cm), the firstmagnet and the second magnet may be used to cause the catheter to assumea preferred orientation within a plane (e.g., the coronal plane) of thepatient. The length of the second magnet allows the second magnet to beattached to the skin of the patient within the coronal plane of thepatient at a pre-determined angle relative to the patient's longitudinalaxis. Similarly, the length of the first magnet allows the first magnetto be attached to the catheter at a pre-determined angle relative to thelongitudinal axis of the catheter. Upon insertion of the catheter andthe first magnet into the vasculature of the patient, the north andsouth poles of the first magnet and the south and north poles of thesecond magnet, respectively, will align. The pre-determined angles ofthe first and second magnets can be chosen such that upon alignment ofthe poles of the first and second magnets, the catheter assumes acertain angle relative to the patient's longitudinal axis within thepatient's coronal plane. Similarly, the first magnet can include a firstgroup of two or more spatially separated magnets, and the second magnetcan include a second group of two or more spatially separated magnets.Torque can be applied to the catheter (e.g., in the coronal plane) bysimultaneously applying oppositely direct forces to two magnets in thefirst group of magnets using the second group of magnets. This can alsoallow the catheter to be fixed in a preferred orientation relative tothe patient's heart, blood vessels, and other surrounding anatomicalfeatures. For example, applying such a torque can change the rotationalposition of the flexible atraumatic extension relative to the coronalplane and relative to the patient's ventricle in order to avoid internalcardiac structures such as chordae and/or the mitral valve. As anotherexample, if the distal portion includes one or more bends, during of thedevice through the aorta and into the ventricle, the cannula and theflexible atraumatic extension may be angled toward a wall of theventricle as shown in FIG. 10 in order to avoid the chordae and/ormitral valve.

FIG. 10 is a cross section of a heart 1000 showing two such rotationalpositions of a catheter within the heart 1000. FIG. 10 shows the heart1000, the left ventricle 1007, the apex 1009 of the left ventricle 1007,the aorta 1001, the aortic valve 1008, the mitral valve 1002, thechordae 1004 of the mitral valve 1002, a first rotational position 1005of a catheter 1010, and a second rotational position 1003 of thecatheter 1010. The catheter 1010 includes magnets 1112 and 1114. In thefirst rotational position 1005, the catheter 1010 extends from the aorta1001, through the aortic valve 1008, and into the left ventricle 1007.When the catheter 1010 is inserted down through the aorta in thisorientation with the bend and the flexible atraumatic protrusion facingtoward the mitral valve, the distal portion of the catheter 1010 such asthe inlet ports and/or the protrusion may unintentionally contact thechordae 1004 of the mitral valve 1002. Inserting the catheter 1010through the aorta in this first rotational position 1005 may beundesirable because contact with the chordae may complicate retractionof the catheter 1010 from the left ventricle 1007 and/or may interferewith or block the inlet port(s) of the catheter 1010, decreasing theamount of blood that can be pumped from the left ventricle into theaorta.

To avoid these challenges, a physician may use the magnets 1112 and 1114to apply torque to the catheter 1010 to rotate the catheter 1010 fromthe first rotational position 1005 to a third rotational position (notshown) that is similar to the rotational position 1003, but will avoidcontacting the chordae and mitral valve. This torque can be applied viaexternal magnets (not shown), such as the second magnet 109 of FIG. 1.The distance separating the magnet 1112 from the magnet 1114 provides asufficient lever arm for supplying the necessary torque. The lever armmay be 5 mm, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 100 mm,200 mm, or any suitable length. Although the magnets 1112 and 1114 areshown on the portion of the catheter 1010 located in the aorta, anysuitable placement of the magnets 1112 and 1114 may be used. In someimplementations, a single magnet can be used to provide the torque if ithas a sufficient length for providing a lever arm (e.g., 3 mm, 5 mm, 10mm, 20 mm, 50 mm, or any other suitable length). Thus, applying torqueusing magnets 1112 and 1114 can allow a user to rotate the catheter 1010to a more desirable position to avoid anatomical structures such as themitral valve and/or chordae.

Substantially fixating the position and/or orientation of the cathetercan improve the effectiveness of the therapeutic and/or diagnosticprocedures to which the catheter is directed. For example, substantiallyfixating a percutaneous catheter configured as a heart pump in itsoptimal position and orientation within the heart can improve cardiacassistance. Substantially fixating the position and orientation of thecatheter may be especially beneficial for therapeutic or diagnosticprocedures requiring a catheter to remain in a patient's vasculature fora long period of time, because the catheter would be less likely tostray from its optimal position and orientation.

The foregoing is merely illustrative of the principles of thedisclosure, and the apparatuses and methods can be practiced by otherthan the described embodiments, which are presented for purposes ofillustration and not of limitation. It is to be understood that theapparatuses and methods disclosed herein, while shown for use inpercutaneously inserted catheters, may be applied to apparatuses andmethods to be used in other types of therapeutic and diagnostic devicesand methods.

Variations and modifications will occur to those of skill in the artafter reviewing this disclosure. The disclosed features may beimplemented, in any combination and subcombination (including multipledependent combinations and subcombinations), with one or more otherfeatures described herein. The various features described or illustratedabove, including any components thereof, may be combined or integratedin other systems. Moreover, certain features may be omitted or notimplemented.

Examples of changes, substitutions, and alterations are ascertainable byone skilled in the art and could be made without departing from thescope of the information disclosed herein. All references cited hereinare incorporated by reference in their entirety and made part of thisapplication.

1-20. (canceled)
 21. A catheter apparatus comprising: a catheter; aheart pump coupled to a distal end portion of the catheter; a firstmagnet coupled to an exterior surface of the catheter; a second magnetconfigured to be coupled to a patient's skin; a third magnet coupled toa distal tip of the heart pump; and a fourth magnet configured to becoupled to the patient's skin at a position different to that of thesecond magnet; wherein the second magnet exerts a magnetic force on thefirst magnet, and the fourth magnet exerts a magnetic force on the thirdmagnet such that the heart pump is stabilized relative to the second andfourth magnets when the catheter and the first and third magnets arepositioned inside of the patient's body, wherein the first, second,third and fourth magnets are spaced sufficiently far away from eachother such as their magnetic fields do not interfere with each other andthe operation of the heart pump.
 22. The catheter apparatus of claim 21,wherein the second and fourth magnets are sized to be supported by thepatient's body.
 23. The catheter apparatus of claim 21, wherein thesecond and fourth magnets each includes an adhesive coating configuredto fix the respective magnet to the patient's skin.
 24. The catheterapparatus of claim 21, wherein the second and fourth magnets are eachenclosed within a patch that is configured to couple to the patient'sskin.
 25. The catheter apparatus of claim 21, wherein the first andthird magnets are coated with an anti-corrosive layer, compound, ormaterial.
 26. The catheter apparatus of claim 21, wherein the firstmagnet is proximal to the heart pump.
 27. The catheter apparatus ofclaim 21, wherein the third magnet is distal to the distal end portionof the heart pump.
 28. The catheter apparatus of claim 21, wherein thesurface area of the first and third magnets facing the patient's skin iseach approximately equal to 25 square millimeters.
 29. The catheterapparatus of claim 21, wherein the surface area of the second and fourthmagnets in contact with the patient's skin is each approximately equalto 25 square millimeters.
 30. The catheter apparatus of claim 21,wherein the attractive force generated by the first and second magnets,and the third and fourth magnets, are each about 2.5 N.
 31. The catheterapparatus of claim 21, wherein the first, second, third and fourthmagnets each have a north and a south pole, and wherein the first andthird magnets are each coupled to the catheter at predeterminedpositions and with a predetermined orientation such that the catheterassumes a preferred orientation relative to the patient.
 32. A methodfor percutaneously inserting a catheter into a patient comprising:inserting a catheter into the patient's vasculature, the catheter havinga first magnet coupled to an exterior surface of the catheter and aheart pump coupled to a distal end portion of the catheter, the heartpump having a third magnet coupled thereto; positioning a second magnetin a fixed position relative to the patient such that the first andsecond magnets are aligned and exert a force on each other, therebystabilizing the position of the catheter relative to the second magnet;and positioning a fourth magnet in a fixed position relative to thepatient such that the third and fourth magnets are aligned and exert aforce on each other, thereby stabilizing the position of the heart pumprelative to the fourth magnet, wherein the first, second, third andfourth magnets are spaced sufficiently far away from each other such astheir magnetic fields do not interfere with each other and the operationof the heart pump.
 33. The method of claim 32, wherein positioning thesecond and fourth magnets in fixed positions relative to the patientcomprises attaching the second and fourth magnets to the patient's skinwith adhesive.
 34. The method of claim 32, wherein the second and fourthmagnets are each included within a patch and the patch is directlyattached to the patient's skin.
 35. The method of claim 32, wherein thefirst magnet is coupled to a distal portion of the catheter.
 36. Themethod of claim 32, wherein the third magnet is coupled to a distal endportion of the heart pump.
 37. The method of claim 32, wherein thefirst, second, third and fourth magnets each have a north and a southpole, and wherein the first and third magnets are each coupled to thecatheter at predetermined positions and with a predetermined orientationsuch that the catheter assumes a preferred orientation relative to thepatient.